The VHIST project defines a file format specification that allows to embed arbitrary binary data (with structured meta-information and multiple facilities for validation) as documentation of workflows. It includes a platform independent reference implementation of essential features. The format conforms to the PDF and other open standards, is self-describing and particularly suited as an image or meta-image format in the context of multi-modality and functional imaging. VHIST can be used on top of existing workflows without the need to change major applications. The full format specification and a reference implementation have been subjected to an OpenSource license.